U.S. Pat. No. 4,481,404 describes a method to control a pyrolysis cleaning procedure in an oven, said method making use of a gas sensor that responds to the smoke gases generated during the pyrolysis. As soon as the gas sensor detects an excessively high concentration of smoke gas, the heating power of the oven cavity heater is lowered in order to reduce the amount of smoke gas. When the smoke gas concentration then drops to below the critical value, the oven cavity heater is once again supplied with the full heating power. This approach serves to avoid overloading of the oxidation catalyst. The employed gas sensor and the evaluation of its output signals have to be adapted to the type of oven in question.
U.S. Pat. No. 4,954,694 describes a method to automatically end a pyrolysis cleaning procedure in an oven whereby, after the heat source has been switched on, the oxygen concentration in an exhaust-air conduit is measured and the duration of the pyrolysis procedure is determined on the basis of the course of the measured values.
Furthermore, German patent application DE 197 06 186 A1 describes a method in which the temperature of the catalyst is measured by means of a temperature sensor. When a certain temperature threshold value, corresponding to a certain amount of smoke gas, is exceeded, the heater that serves to heat the oven cavity is switched off. The heater is only switched on again once the catalyst temperature has dropped below a threshold value.